System and method for production of a primary fluid, such as oil, from an underground reservoir

ABSTRACT

The invention relates to a system and a method for production of a fluid from an underground reservoir. The system comprises a casing ( 10 ) with an internal tubing ( 11 ). At least one plug-in device to be received in the tubing, Means for wire line installation and retrievement of the plug-in device; Means for (un)locking and means for sealing the plug-in device in the casing. Two secondary fluid lines ( 15 ) alongside the tubing are connectable to the plug-in device for operating. The system comprises one or more plug-in devices, each comprising at least one functional section, wherein for pumping devices the first functional section comprises a drive for a pump, which is connectable to the drive such that the pump lies closer to the reservoir than the drive in the position of use. The plug-in devices can be placed at different positions P1 through P6 in the tubing.

The present invention relates to a system for production of a primary fluid, such as oil, from an underground reservoir, comprising:

A casing to be put into the ground for defining an internal elongate hollow tubing running in the direction of the reservoir;

At least one plug-in device to be received in the tubing, which plug-in device is provided with means for sealing the plug-in device in the tubing;

Means for wire line installation and retrievement of the plug-in device in the tubing;

Means for locking and unlocking the plug-in device in the tubing,

wherein the casing comprises at least two secondary fluid lines running in longitudinal direction substantially parallel to the tubing, which secondary fluid lines are connectable to the plug-in device for operating the plug-in device

A system according to the preamble is known in the art and is described in the Dutch patent application NL8602658. The known system relates to a pumping device for pumping a fluid, especially oil, out of a well to the ground surface.

In the known system the plug-in device comprises a pump and a hydraulic drive for the pump, wherein the drive is arranged at a position below the pump seen in the direction towards the underground reservoir.

The known system has many advantages. The main advantage lies in the use of wire line techniques to pull the pump out of the tubing and change it or repair it and install it afterwards into the tubing, to overcome malfunctions.

The need for expensive work over towers is successfully avoided and loss of production time can be kept to a minimum. Further advantages follow from the noiseless functioning and the environmentally friendly character of the known system.

The invention has for its object to further improve the known system.

The system according to the invention is characterized in that the system comprises a set of two or more plug-in devices, each comprising at least one functional section extending between adjacent sealing means and each providing a different technical function in relation to production of the primary fluid, wherein the first functional section of a first plug-in device comprises a drive for a pump, wherein the pump is connectable to the drive such that the pump lies closer to the reservoir than the first functional section in the position of use.

According to the invention the system provides a set of plug-in devices that are each arranged to perform a specific function. All plug-in devices can be standardized with respect to the dimensions and can be interchanged quickly using the wire line techniques known in the art. The most important function relates to the pumping function and necessitates a drive, preferably a hydraulic drive. According to a further aspect of the invention the position of the pump and the drive are reversed. As seen in the longitudinal direction of the tubing the drive is positioned closer to the surface than the pump. This brings about the important possibility of using a pump with flexible dimensions. The pump capacity largely depends on the dimensions of the pump, which can be adapted to the specific well conditions when using the system according to the invention.

According to the first preferred embodiment the functional section of a second one of the plug-in devices comprises an internal passage for unobstructed flow of the primary fluid. In this first preferred embodiment the plug-in device is arranged as a blind plug allowing testing of the proper functioning of the well. Furthermore this first preferred embodiment allows for water injection or steam injection, which are different techniques used in the field of oil production. Water injection wells can be found both on- and offshore to increase oil recovery from an existing reservoir. It is well known in the art to produce wells in a cyclic steam manner for a few cycles (also known as the huff and puff method) before being put on the steam-flooding regime with other wells.

According to a second preferred embodiment an open cage is connected to the second one of the plug-in devices for accommodating measurement devices, such as temperature, pressure or flow measurement devices. In this second preferred embodiment the plug-in device is arranged to function as an observation plug allowing determination of the prevailing well conditions.

According to a third preferred embodiment the functional section of a third one of the plug-in devices is arranged for injection of a tertiary fluid into the reservoir through the secondary fluid lines, wherein the functional section comprises a number of flow out openings for the tertiary fluid. In this third preferred embodiment the plug-in device allows for injection of gas for gas lifting of the oil out of the reservoir. This third preferred embodiment can also be used to inject chemical solvents to clean the well equipment underground thereby increasing production.

According to a further development of the third embodiment the flow out openings are provided with closure means that are pretensioned in the closed position. The pretension force can be chosen carefully to provide a back pressure and to make sure that there is no leakage of oil emulsion into the secondary fluid lines of the tubing.

According to an alternative embodiment the tertiary fluid is water or gas, wherein the drive is arranged to be driven by the tertiary fluid, wherein the tertiary fluid can be discharged by mixing it with the primary fluid produced by the system.

According to a further preferred embodiment the drive is a hydraulic drive arranged to be driven by a hydraulic fluid to be fed through the secondary fluid lines.

Preferably the pump is a plunger or piston pump, a positive displacement pump or a centrifugal displacement pump.

According to a second preferred embodiment of the system according to the invention a number of plug-in devices comprise at least two functional sections arranged adjacently, such that as seen in the longitudinal direction of the tubing the first functional section is positioned closer to the surface than a second functional section. In a technically superior preferred embodiment the second functional section comprises a pump for production of the primary fluid and the first functional section comprises a drive for the pump, wherein a jet pump or a gas lift valve is arranged in the second functional section between the drive and the pump. Preferably the jet pump is a venturi jet pump. Preferably the drive is a turbo motor drive. Preferably the pump is a centrifugal pump.

The invention also relates to a plug-in device as described as part of the system according to the invention. In an advanced embodiment the plug-in device comprises at least two functional sections arranged adjacently. The two functional sections may be arranged to perform a variety of combinations of functions listed in tables. In a more advanced embodiment each functional section is provided with an inlet and an outlet for connection to the secondary fluid lines. Each functional section may be driven with a suitable power fluid or drive medium in an open or closed configuration.

The invention further relates to a method of which the steps are described in the independent method claim.

The invention will now further be described referring to the appending figures, in which:

FIG. 1A shows a schematic view of a first embodiment of a system according to the invention;

FIG. 1B shows the system of FIG. 1A in cross section;

FIG. 2 shows a first embodiment of a plug-in device as part of the system according to the invention;

FIG. 3 shows a second embodiment of a plug-in device as part of the system according to the invention;

FIG. 4 shows a third embodiment of a plug-in device as part of the system according to the invention;

FIG. 5 shows a fourth embodiment of a plug-in device according to the invention;

FIG. 6 schematically shows a cross section through a typical well bore in which a system according to the invention is present.

FIG. 7A shows a schematic view of part of a second embodiment of a system according to the invention;

FIG. 7B shows another part the system of FIG. 7A in cross section; and

FIG. 7C shows part of the second embodiment of FIG. 7A in more detail.

In all figures equal reference numerals denote equal features.

FIG. 1A shows a schematic view of a part of a system 1 for production of a primary fluid according to the present invention. FIG. 1B shows system 1 in cross section.

System 1 is a Wire line Retrievable Oil Production (WROP) system. System comprises a casing 10 that is to be put into the ground wherein an underground reservoir of primary fluid is present. Casing 10 normally has a tubular shape defining an internal elongate hollow tubing 11 that in the position of use runs in the direction of the reservoir (not shown).

Casing 10 comprises at least two lines 15 for secondary fluids that run in longitudinal direction substantially parallel to the tubing 11. Each line has an inlet/outlet 12, 13 that can be used both as an inlet and as an outlet.

In tubing 11 a plug-in device 20 is received. Locking means lock the plug-in device 20 in place in tubing 11. Suitable locking means are available in the relevant art and may comprise, for example, a landing nipple or a locking mandrel.

The plug-in device 20 is sealed in tubing 11 by suitable sealing means, such as 35 packing 23. According to the invention system 1 comprises a set of two or more plug-in devices each providing a different technical function in relation to production of the primary fluid. In FIGS. 2, 3, 4 and 5 four different embodiments are shown. All of these embodiments are preferably at least in part standardized. In the preferred embodiments shown all plug-in devices comprise a part largely similar to the part shown in FIG. 2. Herein a functional section 24 is present that is arranged according to the function to be fulfilled by the plug-in device. In FIG. 2 a blind plug is shown. In FIG. 3 an observation blind plug is shown. In FIG. 4 a gas (or fluid) injection plug is shown and in FIG. 5 a plug with hydraulic drive and pump is shown.

Each of the plug-in devices can be selected, installed and operated for an optimal production of the primary fluid, as will be described in more detail in the following.

FIG. 2 shows a first embodiment of a plug-in device 20 according to the invention. Plug-in device 20 is a so-called blind plug that can be used to test a production well. Plug-in device 20 comprises a generally tubular body 21. Plug-in device 20 is provided with locking means formed by a locking mandrel 22. Suitable locking mandrels are available in the art. In the preferred embodiment shown four seals 23 are present on the circumference of body 21. The functional section 24 extends between adjacent seals. In this embodiment body 21 comprises an internal passage for substantially unobstructed flow of the primary fluid. The blind plug 20 is useful for checking operational pressures in the secondary fluid lines 15.

Plug-in device 20 is a blind plug closing off the inlet/outlet 12, 13 of the secondary fluid lines 15. Once the plug-in device 20 is locked in position by the locking means 22, the sealing means 23 and part of the body 21 seal off the inlet/outlet 12 and the inlet/outlet 13 of the secondary fluid lines 15 of the tubing 11 (see FIG. 1B). Blind plug 20 is also very useful for water injection, which is commonly used in oil production to increase pressure and thereby stimulate production. The oil is literally swept or displaced in the reservoir.

As an alternative to water steam may be injected using the blind plug 20. Suitable materials and seals need than to be chosen that can withstand the higher temperatures.

FIG. 3 shows a cross section of a second embodiment of a plug-in device according to the invention. Plug-in device 30 according to FIG. 3 has the part 20 shown in FIG. 2. Plug-in device 30 is shown in the position of use wherein an open cage 31 is connected to the body 21 for accommodating measurement devices, such as temperature, pressure or flow measurement devices (not shown). The cage construction 31 will protect the measurement devices during installation respectively retrievement of the plug-in device in respectively out of the tubing. The blind plug 20 will protect the secondary fluid lines 15. Plug-in device 30 is very suitable to observe the flow, temperature and pressure in the well.

FIG. 4 shows a cross section of a third embodiment of a plug-in device 40 according to the invention. Plug-in device 40 is a so-called gas lift plug. In the field of oil production gas lift is commonly used when an oil well has insufficient reservoir pressure to produce oil. Injected gas aerates the fluid to reduce its density. The formation pressure is then to lift the oil column and force the fluid out of the well bore. The plug-in device 40 is arranged for injection of a suitable gas or fluid, called tertiary gas or fluid, through the secondary fluid lines 15. Arrows G indicates the direction of gas flow, while arrows O indicate the direction of flow of oil (emulsion) from the well.

Once the plug-in device 40 is locked in position by the locking means 22, the sealing means 23 surround the inlets 12 and 13 of the secondary fluid lines 15 of the tubing 11 (see FIG. 1B). Suitable openings (not shown) in plug-in device 40 allow for a gas flow G to enter the plug-in device 40 through the inlets.

The functional section 44 comprises a number of flow out openings 45 for the tertiary gas or fluid to mix with the oil emulsion. Preferably flow out openings 45 are closed off with valves 46 that are pretensioned in the closed position by means of springs 47

It is noted that plug-in device 40 can also be used to inject chemical solvents to remove unwanted deposit for example paraffin present in the tubing, lines and other underground production equipment. The parts of plug-in device 40 that come into contact with the chemicals to be injected need to be carefully chosen, but suitable materials are available in the relevant art.

FIG. 5 shows a fourth embodiment of the plug-in device according to the invention. Plug-in device 50 is shown schematically (left) and in cross section (right). Plug-in device 50 comprises a first functional section 54 that is arranged as a drive 55 for a pump 57 that is present in a second functional section 56 connected to the first functional section. Plug-in device 50 is shown in the position of use. It is apparent that in the position of use the second functional section comprising the pump lies closer to the reservoir than the first functional section 54.

Once the plug-in device 50 is locked in position by the locking means 22, the sealing means 23 surround the inlet/outlet 12 and the inlet/outlet 13 of the secondary fluid lines 15 of the tubing 11 (see FIG. 1B). Openings 24 in plug-in device 50 allow for a flow F of hydraulic fluid via the inlet 12 and the outlet 13 to cause rotation R of the drive 55.

In the inserts two types of suitable hydraulic drives are shown. Turbine motor 55-1 or positive displacement motor 55-2 are both available on the market and can be coupled to a suitable pump 57. The drive 55 is arranged to allow for upward passage of the primary fluid that is pumped out of the reservoir. In drives 55-1 and 55-2 a hollow central rod allows for passage of oil.

Examples of suitable pumps are a plunger or piston pump, a positive displacement pump or a centrifugal displacement pump. Preferably a piston pump is used in applications at lower pressure, for instance lower than 70 bars. In higher pressure applications ranging up to 2000 bar, plunger pumps are used. Both types of pumps use a cylindrical mechanism to create a reciprocating motion along an axis thereby building up pressure inside to force fluid through the pump. The overall capacity of the piston pumps and plunger pumps can be calculated using the area of the piston or plunger, the stroke length, the number of pistons or plungers and the speed of the drive. The position of the pump below the hydraulic drive as seen in the direction of the oil reservoir allows the dimensions of the pump to be flexibly adapted to the circumstances of the well.

It is noted that openings 24 are suitable for use in the plug-in device 40 to allow for a gas flow G to enter the plug-in device 40 via the inlets.

According to the invention a method is provided for production of a primary fluid, such as oil, from an underground reservoir, using the system according to the invention. The method according to the invention comprises the following steps:

a) Selecting one of the plug-in devices to be received in the tubing;

b) Installing the plug-in device in the tubing using the wire line installation means;

c) Locking the plug-in device in the tubing;

d) Running and installing the tubing and secondary lines (using suitable plug-in-device adaptors) into the casing in the wellbore;

e) Operating the plug-in device by feeding secondary or tertiary fluid in the plug-in device;

f) Unlocking the plug-in device from the tubing;

g) Retrieving the plug-in device out of the tubing using the wire line retrievement means; and

h) Optionally repeating steps a, b, c, e, f and g for the same or another one of the plug-in devices.

FIG. 6 schematically shows a cross section through a typical well bore 100 in which a system according to the invention is present. The configuration of the well bore may have several layouts with different lengths, depths, angles and dimensions. The well bore configuration shown is just one of many possibilities and serves for illustrational purposes only. P1 through P6 illustrate different positions for the plug-in devices 20, 120 in the tubing 11.

FIG. 7A schematically shows a general view of part of a second embodiment of a system according to the invention and FIG. 7B shows another part of the system of FIG. 7A in cross section. FIG. 7A shows a second embodiment of a plug-in device or WROP-tool 120. FIG. 7B shows part of the casing or WROP-nipple for receiving the WROP-tool. Plug-in device 120 has a first functional section A extending between adjacent seal elements or areas 123 similar to the plug-in device 20. Additionally plug-in device 120 has a second functional section B arranged adjacent to the first functional section A. The second embodiment of the system comprises a plug-in device 120 having two functional sections A and B that are arranged adjacently, such that as seen in the longitudinal direction of the tubing the first functional section A is positioned closer to the surface than the second functional section B. The plug-in device 120 is based on the fourth embodiment 50 shown in FIG. 5.

Table 1 lists a number of preferred embodiments of functional sections of plug-in devices according to the present invention, including the preferred embodiments discussed above. The embodiments of the functional sections of the plug-in devices that are also referred to as WROP-tool elements are denoted by abbreviations of the name thereof. Furthermore the possible position P of the WROP-tools in the well bore configuration of FIG. 6 is listed as well as the position in the functional sections A, B in the second embodiment in FIG. 7A.

Table 2 lists a number of combinations of pairs of preferred embodiments of functional sections in table 1 in said positions A and B of plug-in devices.

In general the WROP-tools can be used in the oil & gas, water, geothermal, the general and nuclear industries. The HLE-lines 15 (Hydra-Lines or Control-Lines) can contain the following medium: Water (emulsion), Hydraulic Oil, Gas and Chemical solvents. Other liquids or gasses are possible.

TABLE 1 BASIC WROP TOOL ELEMENTS Recommended/Optional position in Tool Name Short Description WROP-TOOL WELL-BORE Configuration Name of Tool Remarks A B Position WROP - BLP Blind Plug or Dummy X X 1, 2, 3, 4, 5, 6 WROP - OBP Observation Blind Plug Flow-Temp & Pressure X X 1, 2, 3, 4, 5, 6 WROP - GLV Gas Lift Valve X X 1, 2, 3, 4, 5, 6 WROP - CIV Chemical Injection Valve X X 1, 2, 3, 4, 5, 6 WROP - VJP Venturi Jet Pump X X 1, 2, 3, 4, 5, 6 WROP - SAV Safety Valve Plug Mostly used Offshore X X 1, 2, 3, 4, 5, 6 WROP - CEP Centrifugal Displacement Pump Incl. Motor Drive X 1, 2, 3, 4, 5, 6 WROP - CAP Cavity Displacement Pump Incl. Motor Drive X 1, 2, 3, 4, 5, 6 WROP - PPP Piston Plunger Pump Pulsation Pressure X 1, 2, 3, 4, 5, 6 WROP - PAP Packer (de-) Activated Plug X X 1, 2, 3, 4, 5, 6 WROP - HEX Heat Exchanger Plug Geothermal X X 1, 2, 3, 4, 5, 6 WROP - CHV Check Valve (Ball/Flapper type) X X 1, 2, 3, 4, 5, 6

TABLE 2 COMBINATIONS AND POSSIBLE OPTIONS WITH WROP TOOLS Basic: BLP Basic: GLV Basic: SAV Basic: CJV Basic: VJP Basic: PAP Option Option Option Option Option Option A B A B A B A B A B A B BLP - BLP GLV - BLP SAV - BLP CIV - BLP VJP - BLP PAP - BLP BLP - GLV GLV - GLV SAV - GLV CIV - GLV VJP - GLV PAP - GLV BLP - CIV GLV - CIV SAV - CIV CIV - CIV VJP - CIV PAP - CIV BLP - VJP GLV - OBP SAV - OBP CIV - OBP VJP - OBP PAP - OBP BLP - SAV GLV - VJP SAV - VJP CIV - VJP VJP - VJP PAP - VJP BLP - OBP GLV - SAV SAV - PAP CIV - PAP VJP - PAP PAP - PAP BLP - PAP GLV - PAP SAV - HEX CIV - HEX VJP - HEX PAP - HEX BLP - HEX GLV - SAV SAV - SAV CIV - SAV VJP - SAV PAP - SAV

All preferred embodiments of functional sections for plug-in devices listed in the tables above will be shortly discussed herein below.

The WROP-BLP is a Blind Plug functional section discussed referring to FIG. 2. In short the use of a blind plug is to close the HLE-1 or HLE-2 lines 15, to protect the sealing means in the WROP-Nipple to keep the HLE lines 15 under pressure whilst installing the completion with the HLE lines and/or to secure a good installation. The BLP can be combined with all other WROP Down hole Tools (See Table 2).

The WROP-OBP is an Observation Blind Plug, i.e. an example of a functional section as in plug-in device 30 discussed referring to FIG. 3. The observation blind plug is provided with additional parts for assembling measurement devices onto the plug, such as temperature recording devices, flow meters and recording devices, pressure indicators and recording devices et cetera. The OBP can be combined with all other WROP Down hole Tools (See Table 2).

The WROP-GLV is a Gas Lift Valve functional section similar as in plug-in device 40 discussed referring to FIG. 4. The WROP-GLV is a standard tool element, which can be installed in a standard tubing nipple. Gas is flowing though the HLE-Line(s) and pressured into the WROP-nipple and WROP-GLV tool element sections against a spring or gas loaded bellows. When the gas-pressure is strong enough to press the spring/bellows downwards or upwards (depends on the position of the GLV) the gas can float through small openings in the inside wall of the GLV tool element. The spring/bellows is securing the well pressure and prevents ingress of emulsion into the HLE-lines by closing the openings when the gas pressure in the HLE-lines is not high enough. When the gas pressure is high enough the gas can get out of the tool element, but the well emulsion cannot get into the HLE Lines. The GLV tool element can be combined with all other WROP Down hole tool elements (See Table 2).

The WROP-CIP is a Chemical Injection Valve, i.e. an example of a functional section as in plug-in device 40 discussed referring to FIG. 4. The tool-lay-out is almost equal to the GLV, but the main difference is that instead of gas, a chemical solvent or fluid can be pressed into the wellbore solving paraffin particles. Preferred place of the CIV is below a WROP-GLV or WROP-VJP to solve the hard particles before they enter the Gas-Lift section or the Jet-Pump section. The GLV tool element can be combined with all other WROP Down hole tool elements (see Table 2).

The WROP-VJP is a Venturi Jet Pump i.e. an example of a functional section 56 of a plug-in device 50 discussed referring to FIG. 5. The WROP-Venturi Jet Pumps can be adapted to run in a wide variety of bottom hole cavities and down hole tools. The actual working components of the jet pump are a nozzle, throat and diffuser. These components can be wire line retrievably assembled in a variety of configurations and materials to suit the production requirements and down hole environment by a person skilled in the art. A drive medium or power fluid at high pressure (low velocity) transported from surface down hole by the HLE-Line(s) and to the VJP is converted to a low-pressure (high velocity) jet by the nozzle. The pressure at the entrance of the throat becomes lower as the power fluid rate is increased. When this pressure becomes lower than the pressure in the suction passageway, primary fluid is drawn in from the wellbore.

The primary fluid or suction fluid becomes entrained with the high velocity jet and the pumping action then begins. After mixing in the throat, the combined power fluid and suction fluid is slowed down by the diffuser. Because the velocity is reduced, the pressure increases rising to a value sufficient to pump the combined fluid to the surface. A full range of nozzle and throat sizes should be available to allow power fluid rate and pressure to be varied to meet various flow rates.

To optimize the VJP a WROP-GLV (Gas Lift Valve) can be installed in the upper functional section (Option A), which lifts the primary fluid and thus lowers the hydrostatic pressure on the VJP nozzle. This will be beneficial for the surface installed pump-unit and can decrease the power input into the HLE-Line(s).

WROP-SAV is a Safety Valve functional section for a plug-in device. The Wire-line Retrievable Ball or flapper valve, which is normally closed, is held open by hydraulic control pressure trough the HLE-Line from the surface. The valve operates on a hydraulic piston principle. To open, hydraulic pressure slightly higher than the well pressure is applied to move the piston downward. This pressure unseats a secondary seat, allowing pressure to enter through an equalizing port. Then as additional hydraulic pressure is applied to the piston, it continues downward movement, pushing the flapper open.

The WROP-PPP is a Piston Plunger Pump i.e. an example of a functional section 56 of a plug-in device 50 discussed referring to FIG. 5.

All combinations can be made choosing length and dimensions of the pulse and stroke length within the plug-in device, the pressure rating and the pump capacity can be determined with any required length and dimensions.

The WROP-CEP is a Centrifugal Displacement Pump i.e. an example of a functional section 56 of a plug-in device 50 discussed referring to FIG. 5. All combinations can be made in the quantity, type and dimensions of the centrifugal elements. The driving Motor components (See Table 3 WROP-TMD or WROP-DMD) can be different in speed, torque rates and feeder consumption (e.g. hydraulic oil).

The WROP-CAP is a Cavity Displacement Pump, i.e. an example of a functional section 56 of a plug-in device 50 discussed referring to FIG. 5. The cavity pump consists of a helical rotor and a twin helix, twice the wavelength and double the diameter helical hole in a rubber or metal-to-metal stator. The rotor seals tightly against the stator as it rotates, forming a set of fixed-size cavities in between. The cavities move when the rotor is rotated but their shape or volume does not change. The pumped material is moved inside the cavities.

All combinations can be chosen with respect to the quantity, type and dimensions of the cavity elements. The driving Motor components (See WROP-TMD or WROP-DMD) can be different in speed, torque rates and feeder consumption (e.g. hydraulic oil).

WROP-HEX is a Heat Exchanger Plug-in device. The HEX plug-in device can be used when aerial heat is required or can be attracted. The plug keeps the fluid content for a longer while in a heated zone or attracts the heat during a longer period. Combinations with almost all other WROP-tool elements are possible. Products can be used in General oil wells, Shale Oil (heating up the shale layer) and -Geothermal (extracting heat from down hole) Environments in a closed system without attracting or injecting water.

WROP-PAP is a Packer (de-) Activated Plug. For several reasons it is possible to install more than one packer in the well bore. With the PAP a packer can be installed by keeping pressure on the HLE-Line(s) and de-activating the packer seals. By releasing the pressure the seals are activated and installed, closing off a part of the space between tubing and casing (annulus). These tool elements can be used when several perforated parts of the well bore have to be closed or separated.

The WROP-Check Valve is a spring/bellow loaded ball or flapper type check-valve (non return valve) can basically be assembled optionally under every WROP-configuration. The pre-tension of the spring/bellows can be adjusted to customer requirements.

The Motor Drive for WROP-CEP and WROP-CAP displacement pumps is an example of a functional section 54 of a plug-in device 50 discussed referring to FIG. 5. There are presently two existing motors which both are used as mud-motor for drill strings. As flow-fluid medium mud is used to drive the motors. Both can be easily converted into WROP-Drive Motors and improved with stricter tolerances in conjunction by using hydraulic fluids.

The WROP-TMD: Turbo Motor Drive is an example of a functional section 54 of a plug-in device 50 discussed referring to FIG. 5.

The TMD consists of a set of fixed turning vanes at the top of the motor (the stator vanes) which direct the flow of power fluid or drive medium going down the hole to flow onto a second set of vanes (the rotor vanes) which are pushed around by the flow, causing the drive shaft to which they are connected to rotate.

By combining a series of these stages together into a multi-stage turbine considerable torque and speed can be passed to the CEP or CAP pumps that are attached to the rotating drive shaft. In an open system a hollow axle is used to let the primary fluid produced with the CEP or CAP flow freely upwards. Alternatively, by using both HLE-Lines the Hydra Fluid stream is a closed system.

The WROP-DMD: Displacement Motor Drive is an example of a functional section 54 of a plug-in device 50 discussed referring to FIG. 5 based on the principle developed by, Rene Moineau. The theory states that a helical rotor with one or more lobs will rotate eccentrically when within a stator containing one or more lobs than the rotor. The flow of this power fluid or drive medium transmits power allowing the assembly to rotate and turn the transmission-axle. The length (stages), dimensions and shapes of the Stator and Rotor will determine the speed and torque rates, needed to drive the WROP-CEP and WROP-CAP pumps. By using a hollow axle the primary fluid produced with the CEP or CAP can freely flow upwards. By using both HLE-Lines the Hydra Fluid stream is a closed system.

It is noted that not only Hydraulic fluids can be used to feed the HLE-Lines and thus the down hole WROP-Motors, but it is also possible to use the tertiary fluid like gas, water et cetera as propulsion means or drive media to drive the WROP-Motors. The tertiary fluid can be discharged by mixing it with the primary fluid produced by the system.

When these propulsion means go in the down hole motors they will perform the required movements in the motors. At the end of each motor the propulsion means can be used as injection purpose in a build-in Gas-Lift-Valve, Venturi Jet Pump, whilst the motor rotating movement can be guided downwards and activate to the Centrifugal or Cavity displacement down hole pumps.

As there are two Hydra-Lines (HLE-1 and HLE-2), two extra options have been created for an extra propulsion or production aid to the WROP-tool. The extra lifting or pumping aids will lift the hydrostatic column, so the centrifugal/cavity pumps will be able to produce the reservoir (oil/water/gas) emulsion, i.e. the primary fluid, at an easier way. This will create an enormous benefit to the driving speed and/or torque rates of the centrifugal/cavity displacement pumps.

TABLE 3

EXPLANATIONS OF ABBREVIATIONS CAP Cavity Displacement Pump CEP Centrifugal Displacement Pump CHV Check Valve GDD Gas Displacement Drive GLV Gas-Lift Valve GTD Gas Turbo Drive HDD Hydraulic Displacement Drive HLE-1 Hydra-Line no. 1: (Upper entry in WROP Nipple) HLE-2 Hydra-Line no. 2: (Lower entry in WROP Nipple) HTD Hydraulic Turbo Drive VJP Venturi Jet Pump WDD Water Displacement Drive WTD Water Turbo Drive Remarks (X) In combination with Displacement and/or Turbo Drives * Gas and water can contain emulsions as chemicals etc. ** Other combinations with other types of pumps, plugs etc. may be possible

Table 3 lists a number of preferred embodiments of functional sections of plug-in devices according to the present invention, including the preferred embodiments discussed above. The embodiments of the functional sections of the plug-in devices that are also referred to as WROP-tool elements are denoted by abbreviations of the name thereof.

As shown in table 4 there are lots of options and possibilities to make combinations to re-use the propulsion fluids and gasses as extra stimulation to the CEP/CAP pumping units. The choice of these combinations is depending on the wellbore situation and reservoir circumstances.

Final combination choices will be assembled in one WROP-tool and can be installed by wire line. However, it is also conceivable to use some of the tools in a fixed configuration in a well bore. This is explicitly valid for the combinations listed in table 4.

FIG. 7C shows part of the second embodiment of FIG. 7A in more detail. The second functional section B comprises a pump for production of the primary fluid and the first functional section A comprises a drive for the pump, wherein a jet pump or a gas lift valve is arranged in the second functional section B between the drive and the pump. In the advanced preferred embodiment shown at A1 a Gas Turbo Drive (GTD) and an adjacent Gas Lift Valve (GLV) are powered by Gas G. At B1 a Water Turbo Drive (WTD) is powered by water W. At B2 a Venturi Jet Pump is arranged and at B3 a Centrifugal Displacement Pump (CEP) or a Cavity Displacement Pump (CAP) is arranged. At B4 a Check Valve is present.

The Water Turbo Drive of B1 is shown in more detail comprising a stack of rotors R and Stators S. The Venturi Jet Pump of B2 is shown in more detail comprising a diffuser D, a nozzle N and a throat T. F indicates the production flow comprising the primary fluid.

The system according to the invention has many advantages. In random order improvements of the pump ratio can be reached, shorter CAP/CEP pump can be chosen reducing costs and pump effects can be balanced even better than before. Furthermore profits will rise due to more production out of the reservoir and gas/water/emulsion can be reused for injection into the HLE-Lines.

All WROP-tool configurations are suitable in horizontal and vertical (highly deviated) situations and can be used onshore as well as offshore.

All configurations can be adapted to extreme circumstances as high temperatures, high pressures, H₂S contents etc. The choice of materials will be critical for each configuration.

It is noted that in a plug-in device comprising a combination of a drive and a pump, when installed at one of the positions P1 through P6, the drive is positioned closer to the surface than the pump, as seen in the longitudinal direction of the tubing.

It will be clear that a casing to be put into the ground for defining an internal elongate hollow tubing running in the direction of the reservoir is not an essential part of the system according to the present invention. A suitable casing may already be present in the well bore and the system may be arranged to cooperate there with. The secondary fluid lines running in longitudinal direction substantially parallel to the tubing may then form part of the system. The tubing may be formed of WROP-nipples and pipe parts that are coupled, preferably in a releasable manner, to form the tubing. Suitable pipe parts and coupling means are available in the art.

Furthermore, in case the system is not or no longer needed for production of the primary fluid the first plug-in device with a drive for a pump may be left out of the set.

In the relevant technical field by wire line a cabling technology is meant used by operators of oil and gas wells to lower equipment into the well. In the context of the present invention a flexible cable is used to let the plug-in devices sink into the tubing and/or to pull it up out of the tubing. Several types of flexible cables known in the art are suitable in the context of the present invention, including wire line, such as described in NL8602658, coiled tubing or flexible rod.

The invention is of course not limited to the described and shown preferred embodiments. All possible combinations of the embodiments are hereby disclosed and included expressly. The tables are not exhaustive. The invention relates generally to any embodiment falling within the scope of protection as defined in the claims and as seen in the light of the foregoing description and accompanying drawings. 

1. System for production of a primary fluid, such as oil, from an underground reservoir, comprising: A casing to be put into the ground for defining an internal elongate hollow tubing running in the direction of the reservoir; At least one plug-in device to be received in the tubing, which plug-in device is provided with means for sealing the plug-in device in the tubing; Means for wire line installation and retrievement of the plug-in device in the tubing; Means for locking and unlocking the plug-in device in the tubing; wherein the casing comprises at least two secondary fluid lines running in longitudinal direction substantially parallel to the tubing, which secondary fluid lines are connectable to the plug-in device for operating the plug-in device, Characterised in that the system comprises a set of two or more plug-in devices, each providing a different technical function in relation to production of the primary fluid, each comprising at least one functional section extending between adjacent sealing means, wherein the first functional section of a first plug-in device comprises a drive for a pump, wherein the pump is connectable to the drive such that the pump lies closer to the reservoir than the first functional section in the position of use.
 2. System for production of a primary fluid according to claim 1, wherein the functional section of a second plug-in device comprises an internal passage for unobstructed flow of the primary fluid.
 3. System for production of a primary fluid according to claim 2, wherein an open cage is connected to the second plug-in device for accommodating measurement devices, such as temperature, pressure or flow measurement devices.
 4. System for production of a primary fluid according to claim 1, wherein the functional section of a third plug-in device is arranged for injection of a tertiary fluid into the reservoir through the secondary fluid lines, wherein the functional section comprises a number of flow out openings for the tertiary fluid.
 5. System for production of a primary fluid according to claim 4, wherein the flow out openings are provided with closure means that are pretensioned in the closed position.
 6. System for production of a primary fluid according to claim 4, wherein the tertiary fluid is water or gas, wherein the drive is arranged to be driven by the tertiary fluid, wherein the tertiary fluid can be discharged by mixing it with the primary fluid produced by the system.
 7. System for production of a primary fluid according to claim 1, wherein the drive is a hydraulic drive arranged to be driven by a hydraulic fluid to be fed through the secondary fluid lines.
 8. System for production of a primary fluid according to claim 1, wherein the pump is a plunger or piston pump, a positive displacement pump or a centrifugal displacement pump.
 9. System for production of a primary fluid according to claim 1, wherein a number of plug-in devices comprise at least two functional sections arranged adjacently, such that as seen in the longitudinal direction of the tubing the first functional section is positioned closer to the surface than a second functional section.
 10. System according to claim 9, wherein the second functional section comprises a pump for production of the primary fluid and the first functional section comprises a drive for the pump, wherein a jet pump or a gas lift valve is arranged in the second functional section between the drive and the pump.
 11. System according to claim 9, wherein the jet pump is a venturi jet pump.
 12. System according to claim 9, wherein the drive is a turbo motor drive.
 13. System according to claim 9, wherein the pump is a centrifugal pump.
 14. Plug-in device for production of a primary fluid, such as oil, from an underground reservoir, wherein a casing is to be put into the ground for defining an internal elongate hollow tubing running in the direction of the reservoir, wherein said plug-in device is arranged for wire line installation and retrievement of the plug-in device in the tubing, said plug-in device is arranged for sealing the plug-in device in the tubing, said plug-in device is arranged for locking and unlocking the plug-in device in the tubing, wherein the casing comprises at least two secondary fluid lines running in longitudinal direction substantially parallel to the tubing, wherein said plug-in device is connectable to the secondary fluid lines for operating the plug-in device, said plug-in device comprising at least one functional section extending between adjacent sealing means for providing a technical function in relation to production of the primary fluid.
 15. Plug-in device according to claim 14, wherein the functional section comprises a drive for a pump, wherein the pump is connectable to the drive such that the pump lies closer to the reservoir than the functional section in the position of use.
 16. Plug-in device according to claim 14 comprising at least two functional sections arranged adjacently.
 17. Plug-in device according to claim 16, wherein each functional section is provided with an inlet and an outlet for connection to the secondary fluid lines.
 18. Method for production of a primary fluid, such as oil, from an underground reservoir, whereby a casing is to be put into the ground for defining an internal elongate hollow tubing running in the direction of the reservoir, comprising the steps of: a) Selecting a plug-in devices to be received in the tubing; b) Installing the plug-in device in the tubing using wire line installation means; c) Locking the plug-in device in the tubing; d) Running and installing the tubing and secondary lines into the casing in the wellbore; e) Operating the plug-in device by feeding secondary or tertiary fluid into the plug-in device; f) Unlocking the plug-in device from the tubing; g) Retrieving the plug-in device out of the tubing using wire line retrievement means; and h) Optionally repeating steps a, b, c, e, f and g for another plug-in device, said other plug-in device providing a different technical function in relation to production of the primary fluid. 